The lowpass filter DOES exist and it is enabled by default but the SMD cap is so small (250pF) that it has no effect on sound.I soldered a 100nF cap for the quick test and it was too much and the sound was completely muffled from the right channel, but it proved my theory.The SBPro mixer can disable it just like on a normal SBPro card, this works too.

Now the fun part begins, what Cap value will sound exactly the same as the SBPro?Anyone familiar with the SBPro design especially the components of the lowpass filter part?Can anyone tech/electronics savvy help me solve this mystery and make the YMF71x card the best card around for dos gaming.

I'll start by soldering some aligators or sockets so I can quickly switch the caps.

Friends I need a small recording of Doom with a CT1600 card.Doom setup -> No Music.Doom, idkfa, weapon 4, shoot straight ahead, just hold CTRL for a few seconds.

EDIT:2.2nF, 4.7nF and 10nF sound pretty good.Live recording of me connecting a 4.7nF cap on the fly to the sound card.I can do accurate analysis of the frequency response to choose the perfect Cap value, but I need a CT1600 recording.

Replace C11 and C19 (left and right) with 6.8nF capacitors, preferably 0805 (2012) 6.8nF SMD Capacitors.This will make the YMF71x sound similar to the real SBPro which has a functional Lowpass filter, and now the YMF71x has too.After many capacitors and frequency analysis I found that 6.8nF is the most accurate value and sounded closest to the CT1600 example firage provided, even closer than DOSBox.

So now along with the SB = 1 mixer fix and the modification it makes my Yamaha YMF719 the best DOS card I own.

badmojo wrote:Amazing! The lack of filtering has always been one of the things that bothered me about these cards so colour me interested in a mod to fix that

The SB=1 fix and the filter cap mod makes the YMF a though card to beat.No Single-Cycle DMA bugs (clicking and ringing), no MPU-401 bugs, no mixer bugs (now), no noise, and now a proper lowpass filter.The only disadvantage is no ADPCM 2/3bit to 8bit support.

I have to check my YMF-718 cards, i think i only own 1 YMF-719, but i guess it should be easy to find the caps on the 718's too. I will probably use SMD caps, just need to make sure i get the right size.

Are we talking about those two mica ceramic capacitors (yellow)? I thought those were considered through hole caps, not SMD caps. You've soldered them to the surface since there are no vias there, so yes, they are mounted to the surface. But they are intended to be through hole caps, right?